Rally has a plugin oriented architecture - in other words Rally team is trying to make all places of code pluggable. Such architecture leads to the big amount of plugins. Rally Plugins Reference page contains a full list with detailed descriptions of all official Rally plugins.
Rally provides an opportunity to create and use a custom benchmark scenario, runner, SLA, deployment or context as a plugin:
Plugins can be quickly written and used, with no need to contribute them to the actual Rally code. Just place a python module with your plugin class into the /opt/rally/plugins or ~/.rally/plugins directory (or its subdirectories), and it will be autoloaded. Additional paths can be specified with the --plugin-paths argument, or with the RALLY_PLUGIN_PATHS environment variable, both of which accept comma-delimited lists. Both --plugin-paths and RALLY_PLUGIN_PATHS can list either plugin module files, or directories containing plugins. For instance, both of these are valid:
rally --plugin-paths /rally/plugins ...
rally --plugin-paths /rally/plugins/foo.py,/rally/plugins/bar.py ...
You can also use a script unpack_plugins_samples.sh from samples/plugins which will automatically create the ~/.rally/plugins directory.
To create your own plugin you need to inherit your plugin class from plugin.Plugin class or its subclasses. Also you need to decorate your class with rally.task.scenario.configure
from rally.task import scenario
@scenario.configure(name="my_new_plugin_name")
class MyNewPlugin(plugin.Plugin):
pass